Switch to a more reliable method of passing the git-version targt the data it needs

cmake/OpenMWMacros.cmake

@@ -166,11 +166,15 @@ macro (openmw_add_executable target)
 endmacro (openmw_add_executable)
 
 macro (get_generator_is_multi_config VALUE)
-	if (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
-		get_cmake_property(${VALUE} GENERATOR_IS_MULTI_CONFIG)
-	else (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
-		list(LENGTH "${CMAKE_CONFIGURATION_TYPES}" ${VALUE})
-	endif (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
+	if (DEFINED generator_is_multi_config_var)
+		set(${VALUE} ${generator_is_multi_config_var})
+	else (DEFINED generator_is_multi_config_var)
+		if (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
+			get_cmake_property(${VALUE} GENERATOR_IS_MULTI_CONFIG)
+		else (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
+			list(LENGTH "${CMAKE_CONFIGURATION_TYPES}" ${VALUE})
+		endif (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
+	endif (DEFINED generator_is_multi_config_var)
 endmacro (get_generator_is_multi_config)
 
 macro (copy_resource_file source_path destination_dir_base dest_path_relative)

components/CMakeLists.txt

@@ -5,7 +5,8 @@ set (VERSION_IN_FILE "${OpenMW_SOURCE_DIR}/files/version.in")
 set (VERSION_FILE_PATH_BASE "${OpenMW_BINARY_DIR}")
 set (VERSION_FILE_PATH_RELATIVE resources/version)
 if (GIT_CHECKOUT)
-  add_custom_target (git-version
+    get_generator_is_multi_config(multi_config)
+    add_custom_target (git-version
        COMMAND ${CMAKE_COMMAND}
             -DGIT_EXECUTABLE=${GIT_EXECUTABLE}
             -DPROJECT_SOURCE_DIR=${PROJECT_SOURCE_DIR}
@@ -18,7 +19,7 @@ if (GIT_CHECKOUT)
             -DOPENMW_VERSION=${OPENMW_VERSION}
 			-DMACROSFILE=${CMAKE_SOURCE_DIR}/cmake/OpenMWMacros.cmake
 			"-DCMAKE_CONFIGURATION_TYPES=${CMAKE_CONFIGURATION_TYPES}"
-			"-DCMAKE_GENERATOR=${CMAKE_GENERATOR}"
+			-Dgenerator_is_multi_config_var=${multi_config}
             -P ${CMAKE_CURRENT_SOURCE_DIR}/../cmake/GitVersion.cmake
             VERBATIM)
 else (GIT_CHECKOUT)